Key Concepts in Chemistry: Gases, Reactions, and Bonds

Molar Volume of Gases

1 mole of any gas occupies 22,4 dm³ at 0 °C (273 K) and 1 atmosphere (101,3 kPa).

Dipole-dipole Forces

Forces between two polar molecules.

Induced Dipole Forces (London Forces)

Forces between non-polar molecules.

Hydrogen Bonding

Forces between molecules with hydrogen covalently bonded to nitrogen, oxygen, or fluorine.

Boiling Point

Temperature at which vapour pressure equals atmospheric pressure.

Melting Point

Temperature at which solid and liquid phases are at equilibrium.

Vapour Pressure

Pressure exerted by vapour at equilibrium with its liquid in a closed system.

Organic Molecule

Molecules containing carbon atoms.

Molecular Formula

Formula showing elements and numbers of each atom in a molecule.

Structural Formula

Shows which atoms are bonded and includes all bonds.

Condensed Structural Formula

Shows bonding order but omits bond lines.

Hydrocarbon

Organic compounds consisting only of hydrogen and carbon.

Homologous Series

Series where each member differs by a CH₂ group.

Saturated Compound

Compounds with only single bonds between carbon atoms.

Unsaturated Compound

Compounds with one or more multiple bonds between carbon atoms.

Functional Group

Specific bond or atom/group determining properties of compounds.

Structural Isomer

Compounds with the same molecular formula but different structures.

Heat of Reaction (ΔH)

Energy absorbed or released in a chemical reaction.

Exothermic Reaction

Reaction that releases energy.

Endothermic Reaction

Reaction that absorbs energy.

Activation Energy

Minimum energy required for a reaction to occur.

Activated Complex

Unstable transition state from reactants to products.

Reaction Rate

Change in concentration of reactants or products per unit time.

Kw (Ion Product of Water)

Equilibrium constant for ionisation of water: Kw = [H₃O⁺][OH⁻] = 1 × 10⁻¹⁴ at 298 K.

Hydrolysis

Reaction of a salt with water.

Equivalence Point

Point where acid and base have completely reacted in a titration.

Endpoint

Point where the indicator changes colour during a titration.

Galvanic Cell

A cell where chemical energy is converted into electrical energy.

Oxidation (electron transfer)

Loss of electrons.

Reduction (electron transfer)

Gain of electrons.

Oxidation (oxidation number)

Increase in oxidation number.

Reduction (oxidation number)

Decrease in oxidation number.

Oxidising Agent

Substance that is reduced (gains electrons).

Reducing Agent

Substance that is oxidised (loses electrons).

Anode

Electrode where oxidation occurs.

Cathode

Electrode where reduction occurs.

Electrolyte

Substance whose aqueous solution contains ions and can conduct electricity.